1. Field of the Invention
The present invention relates to a clamping apparatus, for example, an apparatus suitable for positioning and fixing a work pallet to a table of a machine tool or a clamp pallet.
2. Explanation of Related Art
A conventional example of the clamping apparatus of this king was disclosed in Japanese Patent Public Disclosure No. 11-10468. The conventional technique is constructed as follows.
A plurality of positioning pins project downwards from a peripheral portion of an under surface of a work pallet. When clamping, first, the work pallet is positioned to an upper surface of a table of a machine tool through the plurality of positioning pins and then a cylinder provided on the table pulls a nipple of the work pallet, thereby fixing the work pallet to the table.
However, the conventional technique requires a horizontal fitting gap between the respective positioning pins and the respective contact surfaces of the table so as to smoothly attach the work pallet to the table. The existence of the fitting gap decreases the positioning preciseness of the work pallet with respect to the table.
The present invention has an object making it possible to smoothly and precisely position and fix a work pallet or the like second block to a table, a clamp pallet or the like first block.
In order to accomplish the object, the present invention has constructed a clamping apparatus, for example, as shown in FIGS. 1A to 1C, FIG. 2 and FIG. 3 or in FIG. 4.
The clamping apparatus positions and fixes a second block 2 to a first block 1. A plurality of positioning means 4, 5 and at least one clamping means 6 are spaced apart from each other. Each of the positioning means 4, 5 includes a positioning hole 23 provided by opening the second block 2, a plug portion 27 projecting from the first block 1 so as to be inserted into the positioning hole 23, and an intermediate member 30 interposed between the plug portion 27 and the positioning hole 23 and able to diametrically expand and contract. The intermediate member 30 is supported by one of the plug portion 27 and the positioning hole 23 axially and movably within a predetermined range and can make a tapering engagement with the other. The intermediate member 30 has a tapered surface 33 which is formed so as to narrow toward an inner portion of the positioning hole 23. The intermediate member 30 is urged by a resilient member 31 in a direction for tightening the tapering engagement. The clamping means 6 pulls the second block 2 to the first block 1.
The present invention, for instance, functions as follows.
When fixing a work pallet or the like second block to a table, a clamp pallet or the like first block, the both blocks are made to approach to one another. First, the plurality of positioning means position the both blocks and then at least one clamping means fixes the both blocks.
More specifically, first, the tapered surface of the intermediate member of every positioning means exerts a guide action, which allows the corresponding each positioning hole to automatically make an aligning movement. Accordingly, each of the positioning holes has an axis precisely coincident with an axis of every plug portion of the first block. A supported surface of the second block contacts or approaches a supporting surface of the first block. Thereafter, the clamping means pulls the second block to the first block, thereby pushing the supported surface to the supporting surface.
Owing to the above arrangement, the second block is constrained by the plug portions through the tapered surfaces of the intermediate members as well as by the supporting surface.
Thus it is possible to smoothly and precisely position and fix the second block to the first block. Besides, in order to achieve the advantage, the positioning means and the clamping means are provided independently. Therefore, each of these means can be readily formed with a simple structure to result in the possibility of manufacturing whole the clamping apparatus at a low cost.
Further, as mentioned above, the positioning means and the clamping means are provided independently. In consequence, when compared with a clamping apparatus where those both means are provided in series with each other, it is possible to reduce a projection height of the table, the clamp pallet or the like first block. When replacing the work pallet or the like second block, this dispenses with the necessity of largely lifting the second block. Additionally, it simplifies a structure of a device for lifting the second block.
The present invention includes the following apparatus.
For example, as shown in FIG. 2 or FIG. 4, the positioning hole 23 is formed by a tapered surface. The tapered positioning hole 23 can make a tapering engagement with the tapered surface 33 of the intermediate member 30. The intermediate member 30 has an inner peripheral surface defined by a straight surface 32. The straight surface 32 is supported by the plug portion 27 axially movably.
The present invention is equipped with the intermediate member in the plug portion of the first block. Therefore, when attaching and detaching a large number of second blocks to one first block, it suffices if the intermediate member is equipped in a smaller number, which results in being able to simplify the structure of the clamping apparatus.
Further, the present invention includes the following clamping apparatus.
For example, as shown in FIG. 3, the clamping means 6 comprises an engaged hole 48 provided in the second block 2, an annular wall 59 projecting from the first block 1 so as to be inserted into the engaged hole 48, a pull rod 61 inserted into the annular wall 59, and an engaging member 63 supported by the annular wall 59. The pull rod 61 is driven for clamping toward a base end, thereby enabling an output portion 64 of the pull rod 61 to pull the second block 2 to the first block 1 through the engaging member 63 and the engaged hole 48.
Moreover, the present invention includes the following clamping apparatus.
For instance, as shown in FIG. 4, the clamping means 6 includes a female screw 79 provided in the first block 1 and a fastening bolt 81 which is attached to the second block 2. The female screw 79 engages with the fastening bolt 81 in screw-thread relationship, thereby allowing the fastening bolt 81 to pull the second block 2 to the first block 1.